FIG. 8 shows one example of a photo-processing apparatus. This photo-processing apparatus comprises a printing part 1 for printing images on the paper and a processing part 2 for carrying out treatments, such as development to the printed paper.
In the printing part 1, there are equipped, along the paper transferring route, a loading part 3 for transferring the paper to the exposure table, an exposure table 4 for exposing and printing the photosensitive paper, an advance part 5 for accurately transferring a predetermined length of the photosensitive paper, a paper transferring part 6 and a stock tank part 7 which can form loops for adjusting the advance of the photosensitive paper to be sent to the processor part 2, and an outlet part 8. In the processing part 2, there are provided a processor rack part 9 in a treatment tank for carrying out color development, bleaching, and fix stabilization; a dryer part 10 in a drying tank for drying the photosensitive paper; and a cutter part 11 in the vicinity of the outlet.
In such photo-processing apparatus, a paper-transferring apparatus is installed for transferring the photosensitive paper, by means of a plurality of rollers, from the process of pulling out a proper amount of photosensitive paper, wrapped and held around a roll magazine (not shown), in a roll form, until the process of finishing the paper into a print, at the processing part 2 are carried out. As shown in FIG. 1A, particularly, the photosensitive paper P sent out onto the exposure stand 4 must be transferred exactly by one print size (a predetermined paper feed size) in view of the fact that an image is printed on it. Therefore, in FIGS. 1A and 1B, the feed roller 22 mounted on the upstream side of the exposure stand 4 and the transferring roller 23 on the downstream side of the transferring route of paper P are both connected to a pulse motor, and are given precisely same number of revolution so that the feed size can be controlled with back tension giving to the paper.
As shown in FIG. 1A, the feed size of the paper P is controlled based on the number of revolution of the feed roller 22 until the head end P1 of the paper P is sandwiched between transferring rollers 23, and as shown in FIG. 1B, the feed size, after the paper is sandwiched between transferring rollers 23, is controlled based on the number of revolution of transferring rollers 23.
Consequently, controlling the number of revolution of both rollers in the same manner gives rise to a problem that the paper is unable to be transferred exactly in the predetermined size if there is any error in the out side diameters of both rollers.
The difference of outside diameter of both rollers is caused not only by processing problems but also by the fact that the outside diameter of the feed roller 22 is intentionally made smaller than that of the transferring roller 23 in order to provide back tension to the paper after it is held between the transferring rollers. In the latter case, in particular, there are rised problems of various inconveniences such as positional discrepancy of the image in the finished print or deviation of the cut size because dimensional deviation becomes remarkable.
There is also a problem of generating waste at the paper head end portion if the paper is exposed after the head end of the paper is held between the transferring rollers.
In addition, there can be assumed a case in which the number of revolution of the feed roller and that of the transferring roller are individually set in advance to feed the predetermined size because of the difference in the outside diameter between the feed roller and the transferring roller. There is, however, a case in which the paper is sandwiched between the transferring rollers before the predetermined size is completely sent out with the feed roller only. In such case, the predetermined size is unable to be sent out unless special countermeasures are taken.
In the above-mentioned paper-transferring apparatus, in general, in order to accurately send the paper to each section stated above, punch holds are drilled near the edge between image frames of the paper, the punch holes are detected at the necessary section by a sensor, and positions of stopping and cutting are determined. Consequently, the accuracy is required for the punch hole position, and back tension is applied to the paper or the paper feed is controlled by a pulse motor to prevent variation of the punch hold position.
However, even if the paper is given back tension or feed-controlled, as described above, there is a problem of inability to improve the positional accuracy of the punch hole as required because the punch hole is drilled with the paper head end not held between the transferring rollers when the paper head end is being exposed. That is, since the paper is sent out to the punch unit by the strength of the paper only, it is difficult to push out and transfer the paper curled by the wrapping in the roll magazine, and, therefore, slack is unavoidably generated in the paper, and it is difficult to accurately arrange the punch hole position. If the paper is transferred and processed in the paper-transferring apparatus with the punch hole deviated, the deviation is generated in the image position in the finished print or defect is generated in the cut size.
Drilling punch holes with the head end held in order to eliminate variation of the punch hole position at the head end generates a great deal of portions in which no punch hole is produced, resulting in loss of the paper.
In addition, in the above-mentioned photo-processing apparatus, in general, a plurality of driving rollers are used and between respective driving rollers, a difference is generated in the roller outside diameters due to processing errors, driving motor control method differs, or roller material is different, thereby generating a difference in the feed rate of each driving roller.
While the apparatus is used over a long time, in each roller, contamination and wear gradually progress. The roller surface becomes slippery due to the contamination and the difference is also generated in the roller outside diameter due to the variation of the degree of wear, and as a result, a difference is generated in the feed rate of each driving roller.
If this error is left as it is, the paper is unable to be transferred in the predetermined sie, and paper slacks or paper pull-out between rollers occurs, causing inconvenience, such as, deteriorated print quality, deviation of cut position or printing position, or paper jamming due to defective transportation.
Consequently, in order to absorb the error of the feed rate of each driving roller, there have been a method of measuring the feed rate per one rotation of each driving roller, comparing the measured value with the theoretical value, increasing or decreasing the feed rate based on the comparison results, and compensating for the error, and a method of providing a buffer to absorb the error (for example, a method of intentionally slacking the paper and pulling it out when more than a predetermined slack volume is formed).
However, even if error is compensated for individual rollers, there is a problem that it is extremely difficult to completely synchronize all the rollers, and there is another problem that even if a buffer is provided, an apparatus for controlling the buffer is required and thus more costs or space are required.
Under the foregoing circumstances, it is an object of the present invention to provide a method of transferring a paper and apparatus used therefor which can constantly provide the predetermined feed size whichever feed roller or transferring roller with a different outside diameter is driven.
More specifically, it is another object of the present invention to provide a method of transferring the paper and apparatus used therefor which can form punch holes accurately in the paper for serving as a positioner during transferring.
Still another object of the present invention is to provide an apparatus of transferring photosensitive material which can apply proper tension to the paper so that the paper traveling condition is good, and which can absorb the error of the feed rate caused by the processing error of the roller outside diameter so that strict roller processing accuracy is not required but cost reduction can be achieved.
The paper-transferring method according to the first embodiment of the present invention comprises mounting a feed roller on an upstream side and a transferring roller on a downstream side with an exposure table located therebetween, and intermittently transferring a strip-form paper onto the exposure table only in the predetermined feed size, and characterized by measuring in advance a feed size of the paper based on number of revolution of the feed roller and a feed size of the paper based on the number of revolution of the transferring roller and compensating for the number of revolution given to both rollers in order to prevent an error generated between both paper feed sizes.
The paper-transferring apparatus according to the first embodiment of the present invention comprises a feed roller mounted on an upstream side and a transferring roller on a downstream side with an exposure table located therebetween, and a control mechanism for controlling numbers of revolution of the both rollers in order to intermittently transfer a strip-form paper onto the exposure table only by a predetermined size, and is characterized in that the control mechanism compensates for the feed size of the paper based on the number of revolution of the feed roller and the feed size of the paper based on the number of revolution of the transferring paper so as to prevent any difference from being generated between the two feed sizes.
In addition, the paper-transferring method according to the first embodiment of the present invention comprises providing a feed roller mounted on an upstream side and a transferring roller on a downstream side with an exposure table located therebetween and a control mechanism for controlling numbers of revolution of the both rollers in order to intermittently transferring a strip-form paper onto the exposure table only by a predetermined size, characterized by controlling the predetermined feed size based on the number of revolution of the feed roller until a paper head end is sandwiched between the transferring roller and controlling the predetermined feed size based on the number of revolution of the transferring roller after the paper is sandwiched between the transferring roller; and if the predetermined size of the paper is unable to be sent out by the feed roller only and is sandwiched between the transferring roller, stopping the rotation of the feed roller just before the paper is sandwiched between the transferring roller, computing the size short for the predetermined feed size by computing the feed size which the feed roller has sent, computing the number of revolution of the transferring roller corresponding to the computer value, and rotating the transferring roller only as much as the computed value.
The paper-transferring apparatus according to the first embodiment of the present invention comprises a feed roller mounted on an upstream side and a transferring roller on a downstream side with an exposure table located therebetween, and a control mechanism for controlling number of revolutions of the both rollers in order to intermittently transferring a strip-form paper onto the exposure table only by the predetermined size, and is characterized in that the control mechanism controls the predetermined feed size based on the number of revolution of the feed roller until a paper head end is sandwiched between the transferring roller and controls the predetermined feed size based on the number of revolution of the transferring roller after the paper is sandwiched between the transferring roller; and if the predetermined size of the paper is unable to be sent out by the feed roller only and is sandwiched between the transferring roller, the control mechanism stops the rotation of the feed roller just before the paper is sandwiched between the transferring roller, and computes the size short for the predetermined feed size by computing the feed size which the feed roller has sent, computes the number of revolution of the transferring roller corresponding to the computed value, and rotates the transferring roller only as much as the computer value.
The paper-transferring method according to the second embodiment of the present invention comprises sending a strip-form paper stored and held with the paper being wrapped in a roll form onto an exposure table by a feed roller and transferring the paper with the head end being sandwiched between the transferring roller, and is characterized by transferring the paper with the paper mask mounted on the exposure table being closed until a head end of the paper is sandwiched between the transferring roller.
It is preferable to keep the paper-transferring speed slower than the normal transferring speed till the paper head end is sandwiched between the transferring roller.
In addition, even if the paper mask is not held closed, it is preferable to only keep the paper-transferring speed slower than the normal transferring speed.
It is preferable to use the paper-transferring method in a paper-transferring apparatus which sends a strip-form paper onto an exposure table by a feed roller, forms punch holes with a punch unit, and transfers the paper with the head end being sandwiched between a transferring roller.
A paper-transferring apparatus according to the second embodiment of the present invention comprises an exposure table for printing and exposing the paper, a paper mask mounted on the exposure table, a feed roller disposed on an upstream side of the exposure table and a transferring roller disposed on a downstream side of the exposure table, and is characterized in that the paper mask is kept closed when a head end of the paper is sent out onto the exposure table with the feed roller until the head end is sandwiched between the transferring roller.
It is preferable to keep the paper-transferring speed slower than the normal transferring speed when the head end of the paper is sent out onto the exposure table with the feed roller until the head end is sandwiched between the transferring roller.
In addition, even if the paper mask is not held closed, it is preferable to only keep the paper-transferring speed slower than the normal transferring speed.
It is preferable to have a punch unit for forming punch holes in the paper between the exposure table and the transferring roller.
A paper-transferring apparatus according to the third embodiment of the present invention comprises a plurality of driving rollers arranged along a transferring route for transferring a strip-form paper via an exposure table, and is characterized in that the relative difference of capabilities of feed rate in the adjoining driving rollers is adjusted to be smaller for driving rollers on an upstream side than for driving rollers on a downstream side.
It is preferable to adjust relative difference of number of revolution in adjoining driving rollers to be smaller for driving rollers on an upstream side than for driving rollers on a downstream side if roller diameters of the adjoining driving rollers are nearly equal.
It is preferable to adjust relative difference of roller diameter in adjoining driving rollers to be smaller for driving rollers on an upstream side than for driving rollers on a downstream side if numbers of revolution of the adjoining driving rollers are nearly equal.
In addition, it is preferable that the adjoining driving rollers are next to each other via the exposure table.
It is also preferable that the driving roller on the upstream side of the adjoining driving rollers is formed with the material with smaller frictional resistance than that of the driving roller on the downstream side and the paper is designed to slip over the driving roller surface on the upstream side if the driving roller on the upstream side of the adjoining driving rollers is disposed so as to come in contact with a base surface of the paper.
Or, it is preferable to form the driving roller on the downstream side of the adjoining driving rollers with the material of smaller resistance than that of the driving roller on the upstream side and the paper is designed to slip over the driving roller surface on the downstream side if the driving roller on the downstream side of the adjoining driving rollers is disposed so as to come in contact with a base surface of the paper.
Furthermore, it is preferable to be constructed in such a manner that a driving roller of the driving rollers disposed so as to come in contact at least with an emulsion surface of the paper has a torque limiter which is designed to operate to cause the driving roller to slip at a driving source before the paper causes slippage on a surface of the driving roller.
In the method of transferring the paper according to the first embodiment of the present invention and the apparatus used therefor, the feed size of the paper based on the number of revolution of the feeding roller is controlled to achieve the same paper feed size based on the number of revolution of the transferring roller by measuring and compensation. Therefore, the predetermined feed size same as that after the paper is sandwiched between transferring roller can be accurately transferred when the paper is sent out only by the feed roller before the paper head end is sandwiched between the transferring roller.
Further, the numbers of revolution of the feed roller and the transferring roller are independently set in advance to send the predetermined feed size, and when the paper is sandwiched between the transferring roller before the predetermined feed size have been sent out, the number of revolution equivalent to that short for the predetermined feed size is given to the transferring roller to send the predetermined feed size.
In the method for transferring the paper and the apparatus used therefor according to the present invention, the paper is guided to a paper mask with the paper mask being closed while the paper head end is sent out onto the exposure table by the feed roller and is sandwiched between the transferring roller, thereby preventing slack of the paper on the exposure table.
By keeping the transferring speed of the feed roller slower than the normal transferring speed while the paper head end is sandwiched, the force for pressing the paper is thoroughly transmitted to the head end of the paper to prevent paper slack.
Paper slack can be prevented more accurately by sending the paper with the paper mask closed while the paper head end is sandwiched as well as by keeping the transferring speed of the feed roller slower than the normal transferring speed.
Moreover, in the paper-transferring apparatus according to the third embodiment of the present invention, if one driving roller of a plurality of driving rollers of the paper-transferring apparatus is designated to a main roller, the main roller does not slip and other driving rollers mounted on the upstream side or on the downstream side of the main roller are likely to be easier to slip than the main roller. If the feed rate of the driving roller on the upstream side of the main roller is reduced, the main roller tries to feed the paper more than the upstream driving roller, and the upstream driving roller slips. It is, therefore, able to apply tension to the paper between the main roller and the upstream driving roller. If the feed rate of the driving roller on the downstream side of the main roller is increased, the feed rate which the main roller feeds to the downstream driving roller decreases. Then, the downstream driving roller slips, and it is, therefore, able to apply tension to the paper between the main roller and the downstream driving roller.
The capability of the feed rate of each driving roller can be adjusted by providing a difference in the outside diameter of each driving roller or by providing a difference in the number of revolution of each driving roller.
It is also possible to easily cause the paper to slip on the outer circumferential surface of the roller by forming the driving roller with the material with a small frictional coefficient.
The driving roller mounted at the position in contact with the emulsion surface of the paper can be slipped without rubbing the paper surface by installing the torque limiter in such a manner that the driving roller is allowed to slip at the driving source.